package com.mk.web.io.netty.http;

import static io.netty.handler.codec.http.HttpHeaderNames.CACHE_CONTROL;
import static io.netty.handler.codec.http.HttpHeaderNames.CONNECTION;
import static io.netty.handler.codec.http.HttpHeaderNames.CONTENT_TYPE;
import static io.netty.handler.codec.http.HttpHeaderNames.DATE;
import static io.netty.handler.codec.http.HttpHeaderNames.EXPIRES;
import static io.netty.handler.codec.http.HttpHeaderNames.IF_MODIFIED_SINCE;
import static io.netty.handler.codec.http.HttpHeaderNames.LAST_MODIFIED;
import static io.netty.handler.codec.http.HttpHeaderNames.LOCATION;
import static io.netty.handler.codec.http.HttpMethod.GET;
import static io.netty.handler.codec.http.HttpResponseStatus.BAD_REQUEST;
import static io.netty.handler.codec.http.HttpResponseStatus.FORBIDDEN;
import static io.netty.handler.codec.http.HttpResponseStatus.FOUND;
import static io.netty.handler.codec.http.HttpResponseStatus.INTERNAL_SERVER_ERROR;
import static io.netty.handler.codec.http.HttpResponseStatus.METHOD_NOT_ALLOWED;
import static io.netty.handler.codec.http.HttpResponseStatus.NOT_FOUND;
import static io.netty.handler.codec.http.HttpResponseStatus.NOT_MODIFIED;
import static io.netty.handler.codec.http.HttpResponseStatus.OK;
import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.RandomAccessFile;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Locale;
import java.util.TimeZone;
import java.util.regex.Pattern;

import javax.activation.MimetypesFileTypeMap;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelProgressiveFuture;
import io.netty.channel.ChannelProgressiveFutureListener;
import io.netty.channel.DefaultFileRegion;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.DefaultHttpResponse;
import io.netty.handler.codec.http.FullHttpRequest;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpHeaderUtil;
import io.netty.handler.codec.http.HttpHeaderValues;
import io.netty.handler.codec.http.HttpResponse;
import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.handler.codec.http.LastHttpContent;
import io.netty.handler.stream.ChunkedFile;
import io.netty.util.CharsetUtil;  
  
/** 
 * A simple handler that serves incoming HTTP requests to send their respective 
 * HTTP responses.  It also implements {@code 'If-Modified-Since'} header to 
 * take advantage of browser cache, as described in 
 * <a href="http://tools.ietf.org/html/rfc2616#section-14.25">RFC 2616</a>. 
 * 
 * <h3>How Browser Caching Works</h3> 
 * 
 * Web browser caching works with HTTP headers as illustrated by the following 
 * sample: 
 * <ol> 
 * <li>Request #1 returns the content of {@code /file1.txt}.</li> 
 * <li>Contents of {@code /file1.txt} is cached by the browser.</li> 
 * <li>Request #2 for {@code /file1.txt} does return the contents of the 
 *     file again. Rather, a 304 Not Modified is returned. This tells the 
 *     browser to use the contents stored in its cache.</li> 
 * <li>The server knows the file has not been modified because the 
 *     {@code If-Modified-Since} date is the same as the file's last 
 *     modified date.</li> 
 * </ol> 
 * 
 * <pre> 
 * Request #1 Headers 
 * =================== 
 * GET /file1.txt HTTP/1.1 
 * 
 * Response #1 Headers 
 * =================== 
 * HTTP/1.1 200 OK 
 * Date:               Tue, 01 Mar 2011 22:44:26 GMT 
 * Last-Modified:      Wed, 30 Jun 2010 21:36:48 GMT 
 * Expires:            Tue, 01 Mar 2012 22:44:26 GMT 
 * Cache-Control:      private, max-age=31536000 
 * 
 * Request #2 Headers 
 * =================== 
 * GET /file1.txt HTTP/1.1 
 * If-Modified-Since:  Wed, 30 Jun 2010 21:36:48 GMT 
 * 
 * Response #2 Headers 
 * =================== 
 * HTTP/1.1 304 Not Modified 
 * Date:               Tue, 01 Mar 2011 22:44:28 GMT 
 * 
 * </pre> 
 */  
public class HttpStaticFileServerHandler extends SimpleChannelInboundHandler<FullHttpRequest> {  
  
    public static final String HTTP_DATE_FORMAT = "EEE, dd MMM yyyy HH:mm:ss zzz";  
    public static final String HTTP_DATE_GMT_TIMEZONE = "GMT";  
    public static final int HTTP_CACHE_SECONDS = 60;  
  
    private final boolean useSendFile;  
  
    public HttpStaticFileServerHandler(boolean useSendFile) {  
        this.useSendFile = useSendFile;  
    }  
  
    /**
     * 类似channelRead方法。
     */
    @Override  
    public void messageReceived(  
            ChannelHandlerContext ctx, FullHttpRequest request) throws Exception {  
        if (!request.decoderResult().isSuccess()) {  
            sendError(ctx, BAD_REQUEST);  
            return;  
        }  
  
        if (request.method() != GET) {  
            sendError(ctx, METHOD_NOT_ALLOWED);  
            return;  
        }  
  
        final String uri = request.uri();  
        System.out.println("-----uri----"+uri);  
        final String path = sanitizeUri(uri);  
        System.out.println("-----path----"+path);  
        if (path == null) {  
            sendError(ctx, FORBIDDEN);  
            return;  
        }  
  
        File file = new File(path);  
        if (file.isHidden() || !file.exists()) {  
            sendError(ctx, NOT_FOUND);  
            return;  
        }  
  
        if (file.isDirectory()) {  
            if (uri.endsWith("/")) {  
                sendListing(ctx, file);  
            } else {  
                sendRedirect(ctx, uri + '/');  
            }  
            return;  
        }  
  
        if (!file.isFile()) {  
            sendError(ctx, FORBIDDEN);  
            return;  
        }  
  
        // Cache Validation  
        String ifModifiedSince = (String) request.headers().get(IF_MODIFIED_SINCE);  
        if (ifModifiedSince != null && !ifModifiedSince.isEmpty()) {  
            SimpleDateFormat dateFormatter = new SimpleDateFormat(HTTP_DATE_FORMAT, Locale.US);  
            Date ifModifiedSinceDate = dateFormatter.parse(ifModifiedSince);  
  
            // Only compare up to the second because the datetime format we send to the client  
            // does not have milliseconds  
            long ifModifiedSinceDateSeconds = ifModifiedSinceDate.getTime() / 1000;  
            long fileLastModifiedSeconds = file.lastModified() / 1000;  
            if (ifModifiedSinceDateSeconds == fileLastModifiedSeconds) {  
                sendNotModified(ctx);  
                return;  
            }  
        }  
  
        RandomAccessFile raf;  
        try {  
            raf = new RandomAccessFile(file, "r");  
        } catch (FileNotFoundException fnfe) {  
            sendError(ctx, NOT_FOUND);  
            return;  
        }  
        long fileLength = raf.length();  
  
        HttpResponse response = new DefaultHttpResponse(HTTP_1_1, OK);  
        //setContentLength(response, fileLength);  
        HttpHeaderUtil.setContentLength(response, fileLength);
        setContentTypeHeader(response, file);  
        setDateAndCacheHeaders(response, file);  
        if (HttpHeaderUtil.isKeepAlive(request)) {  
            response.headers().set(CONNECTION, HttpHeaderValues.KEEP_ALIVE);  
        }  
  
        // Write the initial line and the header.  
        ctx.write(response);  
  
        // Write the content.  
        ChannelFuture sendFileFuture;  
        if (useSendFile) {  
            sendFileFuture =  
                    ctx.write(new DefaultFileRegion(raf.getChannel(), 0, fileLength), ctx.newProgressivePromise());  
        } else {  
            sendFileFuture =  
                    ctx.write(new ChunkedFile(raf, 0, fileLength, 8192), ctx.newProgressivePromise());  
        }  
  
        sendFileFuture.addListener(new ChannelProgressiveFutureListener() {  
            @Override  
            public void operationProgressed(ChannelProgressiveFuture future, long progress, long total) {  
                if (total < 0) { // total unknown  
                    System.err.println("Transfer progress: " + progress);  
                } else {  
                    System.err.println("Transfer progress: " + progress + " / " + total);  
                }  
            }  
  
            @Override  
            public void operationComplete(ChannelProgressiveFuture future) throws Exception {  
                System.err.println("Transfer complete.");  
            }  
        });  
  
        // Write the end marker  
        ChannelFuture lastContentFuture = ctx.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT);  
  
        // Decide whether to close the connection or not.  
        if (!HttpHeaderUtil.isKeepAlive(request)) {  
            // Close the connection when the whole content is written out.  
            lastContentFuture.addListener(ChannelFutureListener.CLOSE);  
        }  
    }  
  
    @Override  
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {  
        cause.printStackTrace();  
        if (ctx.channel().isActive()) {  
            sendError(ctx, INTERNAL_SERVER_ERROR);  
        }  
    }  
  
    private static final Pattern INSECURE_URI = Pattern.compile(".*[<>&\"].*");  
  
    /** 
     * 路径解码 
     * @param uri 
     * @return 
     */  
    private static String sanitizeUri(String uri) {  
        // Decode the path.  
        try {  
            uri = URLDecoder.decode(uri, "UTF-8");  
        } catch (UnsupportedEncodingException e) {  
            try {  
                uri = URLDecoder.decode(uri, "ISO-8859-1");  
            } catch (UnsupportedEncodingException e1) {  
                throw new Error();  
            }  
        }  
  
        if (!uri.startsWith("/")) {  
            return null;  
        }  
  
        // Convert file separators.  
        uri = uri.replace('/', File.separatorChar);  
  
        // Simplistic dumb security check.  
        // You will have to do something serious in the production environment.  
        if (uri.contains(File.separator + '.') ||  
            uri.contains('.' + File.separator) ||  
            uri.startsWith(".") || uri.endsWith(".") ||  
            INSECURE_URI.matcher(uri).matches()) {  
            return null;  
        }  
  
        // Convert to absolute path.  
        return System.getProperty("user.dir") + File.separator + uri;  
    }  
  
    private static final Pattern ALLOWED_FILE_NAME = Pattern.compile("[A-Za-z0-9][-_A-Za-z0-9\\.]*");  
  
    private static void sendListing(ChannelHandlerContext ctx, File dir) {  
        FullHttpResponse response = new DefaultFullHttpResponse(HTTP_1_1, OK);  
        response.headers().set(CONTENT_TYPE, "text/html; charset=UTF-8");  
  
        StringBuilder buf = new StringBuilder();  
        String dirPath = dir.getPath();  
  
        buf.append("<!DOCTYPE html>\r\n");  
        buf.append("<html><head><title>");  
        buf.append("Listing of: ");  
        buf.append(dirPath);  
        buf.append("</title></head><body>\r\n");  
  
        buf.append("<h3>Listing of: ");  
        buf.append(dirPath);  
        buf.append("</h3>\r\n");  
  
        buf.append("<ul>");  
        buf.append("<li><a href=\"../\">..</a></li>\r\n");  
  
        for (File f: dir.listFiles()) {  
            if (f.isHidden() || !f.canRead()) {  
                continue;  
            }  
  
            String name = f.getName();  
            if (!ALLOWED_FILE_NAME.matcher(name).matches()) {  
                continue;  
            }  
  
            buf.append("<li><a href=\"");  
            buf.append(name);  
            buf.append("\">");  
            buf.append(name);  
            buf.append("</a></li>\r\n");  
        }  
  
        buf.append("</ul></body></html>\r\n");  
        ByteBuf buffer = Unpooled.copiedBuffer(buf, CharsetUtil.UTF_8);  
        response.content().writeBytes(buffer);  
        buffer.release();  
  
        // Close the connection as soon as the error message is sent.  
        ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);  
    }  
  
    private static void sendRedirect(ChannelHandlerContext ctx, String newUri) {  
        FullHttpResponse response = new DefaultFullHttpResponse(HTTP_1_1, FOUND);  
        response.headers().set(LOCATION, newUri);  
  
        // Close the connection as soon as the error message is sent.  
        ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);  
    }  
  
    private static void sendError(ChannelHandlerContext ctx, HttpResponseStatus status) {  
        FullHttpResponse response = new DefaultFullHttpResponse(  
                HTTP_1_1, status, Unpooled.copiedBuffer("Failure: " + status.toString() + "\r\n", CharsetUtil.UTF_8));  
        response.headers().set(CONTENT_TYPE, "text/plain; charset=UTF-8");  
  
        // Close the connection as soon as the error message is sent.  
        ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);  
    }  
  
    /** 
     * When file timestamp is the same as what the browser is sending up, send a "304 Not Modified" 
     * 
     * @param ctx 
     *            Context 
     */  
    private static void sendNotModified(ChannelHandlerContext ctx) {  
        FullHttpResponse response = new DefaultFullHttpResponse(HTTP_1_1, NOT_MODIFIED);  
        setDateHeader(response);  
  
        // Close the connection as soon as the error message is sent.  
        ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);  
    }  
  
    /** 
     * Sets the Date header for the HTTP response 
     * 
     * @param response 
     *            HTTP response 
     */  
    private static void setDateHeader(FullHttpResponse response) {  
        SimpleDateFormat dateFormatter = new SimpleDateFormat(HTTP_DATE_FORMAT, Locale.US);  
        dateFormatter.setTimeZone(TimeZone.getTimeZone(HTTP_DATE_GMT_TIMEZONE));  
  
        Calendar time = new GregorianCalendar();  
        response.headers().set(DATE, dateFormatter.format(time.getTime()));  
    }  
  
    /** 
     * Sets the Date and Cache headers for the HTTP Response 
     * 
     * @param response 
     *            HTTP response 
     * @param fileToCache 
     *            file to extract content type 
     */  
    private static void setDateAndCacheHeaders(HttpResponse response, File fileToCache) {  
        SimpleDateFormat dateFormatter = new SimpleDateFormat(HTTP_DATE_FORMAT, Locale.US);  
        dateFormatter.setTimeZone(TimeZone.getTimeZone(HTTP_DATE_GMT_TIMEZONE));  
  
        // Date header  
        Calendar time = new GregorianCalendar();  
        response.headers().set(DATE, dateFormatter.format(time.getTime()));  
  
        // Add cache headers  
        time.add(Calendar.SECOND, HTTP_CACHE_SECONDS);  
        response.headers().set(EXPIRES, dateFormatter.format(time.getTime()));  
        response.headers().set(CACHE_CONTROL, "private, max-age=" + HTTP_CACHE_SECONDS);  
        response.headers().set(  
                LAST_MODIFIED, dateFormatter.format(new Date(fileToCache.lastModified())));  
    }  
  
    /** 
     * Sets the content type header for the HTTP Response 
     * 
     * @param response 
     *            HTTP response 
     * @param file 
     *            file to extract content type 
     */  
    private static void setContentTypeHeader(HttpResponse response, File file) {  
        MimetypesFileTypeMap mimeTypesMap = new MimetypesFileTypeMap();  
        response.headers().set(CONTENT_TYPE, mimeTypesMap.getContentType(file.getPath()));  
    }  
  
}  